1. Field of the Invention
The present invention relates to a videoscope for three-dimensionally viewing a skin, a tissue sample or the like by enlarging it through close-up photography, and its display unit.
2. Description of the Related Art
Though a scope using a solid-state imaging sensing device such as a CCD (hereafter referred to as CCD) is recently used for observation of a skin, it is difficult to identify the irregularity of a skin groove, a skin crest, or lesion. Therefore, a scope allowing three-dimensional observation is requested.
That photographing methods for three-dimensional reproduction include a parallel imaging method of arranging two cameras so that optical axes are parallel and an intersectional imaging method in which optical axes intersect each other is announced through various books and theses including xe2x80x9cFoundation of Three-Dimensional Imagexe2x80x9d edited by NHK Science and Technical Research Laboratories and it is publicly known that an image photographed by the parallel imaging method or intersectional imaging method is deformed and reproduced except a state under a certain condition.
Moreover, three-dimensional display units for reproducing a three-dimensional image include the polarization-filter type using special glasses such as polarization glasses, liquid-crystal shutter type for time-division display of right and left images, and parallax barrier type requiring no glasses, and lenticular type.
As a scope for three-dimensional observation, Japanese Patent Laid-Open No. Hei8-29701 discloses a three-dimensional endoscope having two imaging windows constituted by arranging imaging systems comprising a pair of object lenses and a CCD in parallel or collaterally so as to obtain a binocular parallax and a display unit for displaying right and left images through time division and observing the images by special glasses.
In case of three-dimensional viewing, there is a binocular fusion limit in which binocular fusion is not realized when a binocular parallax increases to a certain degree or higher.
Moreover, when a distance from an object is too small like the case of close-up enlargement, a fusion range of right and left reproduced images is too small in case of the parallel imaging method when a binocular parallax is too large while a degree of trapezoidal deformation of a reproduced image further increases in case of the intersectional imaging method. Thus, it is difficult to obtain a preferable three-dimensional image. Therefore, it is necessary to realize a small binocular parallax.
However, as shown in FIG. 7, the prior art disclosed in Japanese Patent Laid-Open No. Hei8-29701 fixes two imaging systems comprising objective lenses 51R and 51L and CCDs 52R and 52L in parallel or collaterally and images an object from two imaging windows 53R and 53L.
In case of the above configuration, the interval between objective lenses for forming a convergence angle is restricted to the size of an objective lens and it is impossible to realize a very-small binocular parallax necessary for close-up enlargement photography.
Moreover, a display unit 54 of the prior art is inferior in manipulability because it is troublesome to set or remove special glasses 55, a screen image is dark because of using a polarization filter, vertical resolution deteriorates to xc2xd, or a flicker occurs or a double-speed-display converter for preventing the flicker is necessary.
The present invention is made to solve the problems of a conventional three-dimensional videoscope and its object is to provide a display unit capable of obtaining a preferable three-dimensional image through close-up photography and a simple display unit superior in manipulability.
One aspect of the present invention is a videoscope, comprising:
light dividing means for dividing the light incoming from an imaging window and emitted from an object into transmitted light and reflected light;
a first imaging system having at least an objective lens and an imaging device for imaging the transmitted light; and
a second imaging system having at least an objective lens and an imaging device for imaging the reflected light, wherein:
image inverting means for returning a mirror image formed by the reflected light to an orthoscopic image is provided for the second imaging system; and
parallax producing means for producing a parallax for three-dimensionally viewing an image formed by the first and second imaging systems is included.
Another aspect of the present invention is a display unit, characterized by comprising image synthesizing means for producing images for one frame by deleting predetermined areas of a first video signal and a second video signal which are provided with a parallax for three-dimensional viewing so as to leave central portions and arranging video signals of central portions to right and left and outputting the images for one frame as video signals.